Conventionally, capacitors using an electrolytic solution have been known as capacitors using an electrolytic material. However, other than this, techniques of electrical double layer capacitors which have a pair of electrodes provided on surfaces of a solid electrolytic body and use an inorganic solid electrolyte as a material of the solid electrolytic body have been proposed in recent years (see Patent Document 1).
Patent Document 1 discloses that a lithium (Li) ion conductive compound and a sodium (Na) ion conductive compound are contained as an inorganic solid electrolyte.